A Nitrogen Oxide (NOx) sensor may be positioned at various locations in an engine exhaust system, in order to measure a concentration of NOx in exhaust gases exiting an engine. For example, the NOx sensor may be positioned at an exhaust outlet of an aftertreatment system, and/or downstream or upstream of a Selective Catalytic Reduction (SCR) module with respect to a direction of flow of the exhaust gas.
Sometimes, the NOx sensors disposed within the exhaust outlet may get damaged due to entry of water or debris into the exhaust outlet. For example, water in the form of condensed water vapor or rain water may enter into the exhaust outlet and contact a sensing element of the NOx sensor. The water contacting the NOx sensor may damage the sensing element of the NOx sensor. Damage of the sensing element may require the NOx sensors to be replaced.
U.S. Pat. No. 7,818,964 discloses an exhaust system for a motorcycle having an engine mounted on a front half of a body frame of the motorcycle. The system includes a plurality of first exhaust pipes extending from exhaust ports of the engine, a collecting section at which the first exhaust pipes are collected, a second exhaust pipe including a substantially straight portion connected to a downstream side of the collecting section and disposed under a crankcase of the engine, an expansion chamber connected to a downstream side of the second exhaust pipe and located under a rear wheel suspension arranged behind the engine, an exhaust outlet disposed on a most downstream portion of the expansion chamber, and an exhaust throttle valve and an exhaust gas sensor disposed on the straight portion of the second exhaust pipe.